Field of the Invention
The subject matter presented herein relates generally to the field of communications networks, and in particular, to wireless mesh networks.
Description of Related Art
In a large mesh network that uses multiple media, e.g., separate frequencies in a radio frequency (RF) spectrum, some nodes can be typically much busier than other nodes and thus form bottlenecks in the mesh. Examples of these nodes include access points (APs) or gateways that are controlling endpoints in the mesh or are receiving information from a multiplicity of nodes.
While a possible solution to the bottleneck problem is to expand the number of APs, there are limitations to such an approach. For example:                1) cost increases almost linearly with the number of APs,        2) laws of physics impose limitations between transmitters and receivers that are closely co-located, and        3) regulations in unlicensed spectra restrict collaboration between unlicensed nodes for the purposes of eliminating mutual interference.        
Regarding this latter point, limitations placed on Frequency Hopping Spread Spectrum (FHSS) devices certified under 47 CFR 15.247, which is promulgated by the U.S. Federal Communications Commission (FCC), (and more generally, any certified unlicensed devices worldwide), are designed to provide opportunities for sharing unlicensed portions of the RF spectrum in an radio-egalitarian manner. Power limits, channel occupancy (cumulative dwell time), bandwidths, etc., all have specified limits to permit co-existence of mutually compatible devices.
Some applications of these radios have included classic point-to-point communications. For example, IEEE Standard 802.11 “WiFi” has been developed to provide interoperable equipment with the purpose of transporting digital information over short distances. Applications requiring greater range have attempted to mesh multiple radios together to form a network where communications hop from node to node in a process called routing to travel from the source to the destination. Network operation within this mesh is performed in a peer-to-peer fashion, where network maintenance and overhead traffic is sent between all adjacent nodes in order to keep the network communicating efficiently and robustly.
Mesh networks have proven very successful, and many examples of large, geographically distributed networks exist. The architecture of these networks typically supports a process control model where there are just a few nodes, known as access points (APs), which provide access into and egress from the mesh network. A multiplicity of endpoint nodes in the mesh network can be accessed from these access point entry nodes. Requests and commands are sent through APs, and responses and acknowledgements are returned through them. When it is desired to communicate with a large number of endpoint nodes, the concentration of traffic at the APs may cause a traffic bottleneck in the mesh network.
Several schemes have been used to address these limitations. Some of these schemes are directed to the amount of data or the manner in which it is transmitted, such as:                Data compression (sending fewer bytes of data to reduce bandwidth requirements at the APs),        Autonomous messaging (sending data in only one direction), and/or        Coordinating or scheduling data traffic via both time (temporal) and prioritization (queuing techniques).        
Other schemes are directed to the infrastructure of the mesh network, e.g., emplacing more APs within the wireless network coverage, in an attempt to solve the congestion problem. For instance, multiple APs might be operating in parallel at a particular location. However, this approach is burdened with linearly increasing, and often prohibitive, expense.